You will need
Calculation of electricity consumed by a computer is the sum of the capacities of all its components. Find out the capacity of the main component, i.e. the Central processor. The higher the frequency, the more energy will be consumed.
Add to the previous value of capacity which is consumed by the motherboard. The average value usually varies in the range of 20 watts.
To this amount add the power consumed by the graphics card. The average is 100 watts.
To the previous value add to the capacity of the RAM module. The larger the module, respectively, will consume more electricity. The average value of the power module RAM – 15 watts.
Add to the sum capacity of the hard drive. Consumed them the power depends on running processes. While playing on the computer, power is consumed more than while browsing the site.
To the previous value, add the capacity of all available drives. This value usually varies between 20 W and depends on the speed of rotation and frequency of use.
Add to the sum of the power consumption of a floppy drive. This value is standard for all manufacturers and is 7 watts.
To the previous number add power which is consumed by the sound card. The better the sound card, the greater its power. The average value in the range of 10 watts.
To the previous sum, add the power consumed USB port, LPT port and COM ports. The average value of 9 watts.
The final number you want to add to see how much electricity the computer consumes power network card. The average is 4 watts.
Remember that excessive consumption of electricity may cause fire.
The power consumption is significantly reduced, if you use the computer "sleep" mode.